Increasing the molecular weight of polyethylene (and copolymers of ethylene) generally results in enhancing tensile strength, ultimate elongation, impact strength, puncture resistance, and toughness, of films produced therefrom. However, increasing the molecular weight of the polyethylene will usually decrease its processability. By providing a mixture of a high molecular weight polyethylene with a lower molecular weight polyethylene, the desirable characteristics due to the high molecular weight component can be retained while improving processability of the mixture containing the high molecular weight component. To produce such mixtures, various alternatives are being considered, including post reactor or melt blending, catalysis in a single reactor with a catalyst effective to produce such a product and lastly use of multistage reactors, in which diverse average molecular weight components can be produced in each reactor. In accordance with the invention, the bubble stability of resins produced far surpass those produced by other mixed metal catalyst(s).